OKLAHOMA CITY – Officials have determined the cause of a fire that put one man in the hospital in critical condition on Monday.

Just after 8:15 p.m., firefighters responded to the 9300 block of S. Hudson to check a report of smoke in the area.

When crews arrived, they found smoke and flames coming from a tri-plex structure.

A neighbor told firefighters the homeowner rarely left the house and may have still been inside.

Crews were able to force entry into the structure and started searching for the homeowner.

They found the man in the living room area and he was quickly removed and given medical treatment. Firefighters administered a specialized Cyano-Kit, an antidote for Cyanide poisoning, before he was taken to the hospital in critical condition.

The fire was extinguished, and two other units of the Tri-Plex sustained damage.

The fire caused approximately $90,000 property and content loss. The property and content value is $111,000.

The cause of the fire was due to unattended cooking. There were no reports of any other injuries.

Fire officials say there was a smoke detector present, but it was not operable.